Author 
Shaykh  Al Zahranī
The early Muslims paid great attention to recording everything that was reported from the Prophet, peace and blessing be upon him, whether verbal, practical or tacit approval, because it is the second source of Islamic legislation. The process of that recording passed through several stages of codification, then writing, classification, and authorship, after it was limited only to word of mouth and narration. Then, with the passage of time, the types of Hadith and Sunnah books branched out between Sahih, Sunan, Muwattas, compilations, chains of narrators, Mustadraks and extracts, which contain thousands of prophetic Ahadiths and honorable narration.
This on the preservation of the Sunnah & its codification in the first centuries, and then of the development of classification and writing it through the Hijri centuries, with a brief definition of the famous scholars of this scientific movement, as well as the most important books they wrote in those centuries.      Pges. 263